1. Technical Field
The present invention relates generally to methods for generating, isolating, and expanding antigen-specific T cells. The present invention also relates to compositions of antigen-specific T cells.
2. Description of Related Art
The identification of antigens recognized by T cells in a variety of cancers and infectious diseases has contributed significantly to the interest in the use of antigen-specific immunotherapy for the treatment of malignancies and infectious diseases. Adoptive therapy using antigen-specific T cells represents a conceptually attractive strategy by providing a means to manipulate the specificity, phenotype and magnitude of the intended immune response. Methods to routinely and reproducibly expand antigen-specific T cell clones for use in clinical trials of adoptive therapy would be desirable. Current technologies for generating therapeutic doses of antigen-specific T cells remain limited and could be improved by simplifying the manufacturing process while maintaining or perhaps improving the function of the infused T cells.
The various techniques available for expanding human T-cells have relied primarily on the use of accessory cells (primarily antigen presenting cells (APC)) and/or exogenous growth factors, such as interleukin-2 (IL-2). IL-2 has been used together with an anti-CD3 antibody to stimulate T-cell proliferation, predominantly expanding the CD8+subpopulation of T-cells. Both APC signals are thought to be required for optimal T-cell activation, expansion, and long-term survival of the T-cells upon re-infusion. The requirement for MHC-matched APCs as accessory cells presents a significant problem for long-term culture systems because APCs are relatively short-lived. Therefore, in a long-term culture system, APCs must be continually obtained from a source and replenished. The necessity for a renewable supply of accessory cells is problematic for treatment of immunodeficiencies in which accessory cells are affected. In addition, when treating viral infection, if accessory cells carry the virus, the cells may contaminate the entire T-cell population during long-term culture.
Further, similar syStems require vaccination with antigen (e.g. tumor/viral antigen), pulsing of antigen-presenting cells with antigens followed by infusion of cells. Expansion of antigen-specific T cells to generate large numbers of antigen-specific T cells often requires labor intensive and expensive cloning, and/or multiple rounds of activation/expansion to achieve therapeutically relevant T cell numbers.
Therefore, there is a need in the art for improved methods to routinely and reproducibly expand antigen-specific T cell clones for use in clinical trials of adoptive therapy and for a simplified manufacturing process that maintains or even improves the function of the antigen-specific T cells.
The present invention provides methods to generate an increased number of highly responsive antigen-specific T cells that have surface receptor and cytokine production characteristics that are more desirable than other expansion methods. The instant invention does not require knowledge of a particular antigen (although known antigens can be used in the context of this invention) and provides for a single, or double, round of expansion to achieve a therapeutically relevant dose of antigen-specific T cells, both of the CD4 and CD8 lineage (and either may be selected if desired).